Telephone system



July 7, 1942- T. F. cRocKr-:R 2,288,789

TELEPHONE SYSTEM Filed March 29, 1940 7 Sheets-Sheet l A, .mmv .mul ifmmw wml@ m QN zw 45,3

INVENTOR THOMAS F. CROCKER ATTORNEYS T. F. cRocKER TELEPHONE SYSTEMFiled March 29, 1940 July 7, 1942.

7 Sheets-Sheet 2 @QN .w20 m23 m5@ Nummm INVENTQR THOMAS F. cRocKaRATTORNEYS July 7, 1942.v rr. F. cRocKER TELEPHONE SYSTEM Filed March 29,1940 7 Sheets-Sheet 3 m ONM.

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TELEPHONE SYSTEM Filed March 29, 1940 7 Sheets-Sheet 4 @Sv Etam m bmw/mFv 4 INVENTOR THOMAS E CROGKER ,M :KY/M1 ATTORNEYS Julyv 7", 1942.y

T. F. CROCKER TELEPHONE SYSTEM Filed March 29. 1940 `7 sheets-sheet 5July 7, 1942.

T. F. CROCKER l1"ELEPHONE SYSTEMl Filed March 29, 1940 7 Sheets-Sheet, 6

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I ollakmmb INVENTOR' THOMAS F. CROCKER ,am BY al M l l ATTORNEYSPatented July 7, 1942 1 'Thomas Crocker, Chicago, Ill., assgnor 4to As-Isociated 'Electric Laboratories, `In'ci, Chica-go,

'IlL, -a corporation of Delaware Application March 2.9, 1940, Serialo..32li6l9 erom-rms; (ci-risate) The present invention relatestotelephonel systems and moreparticularly to improved semiautomatictelephone systems-ofl the character of that disclosed and claimed in thecopending application `of Thomas F. Crocker; Serial No. 311,1551, ledDecember 29, 11939.

In a 4conventional telephone system of the semi-'automatic typ-e, thevarious manual telephonev lines terminate, injackswat the A and lBoperator positions; and an automatic switch train provided with adistributin'gfsystem is in.-

'terposed between the A operatorpositions and theB operator positions.Ina telephone system of this type, calls son theV telephone :lines areanswered directly by the operators at the A operator positions and:routed by way of the switch train underthe lcontrol of thedistributing'system to the s-B operatorpositions to be completed.

Hence, in a'telephone's'ystemof this type, the

`traflic between the Agoperator positions and the Boperator'positionsisgovernedby the rdistributing system. However, the traffic betweenthecalling .telephone lines `of tlievarious A operator positionszis'not`governed butz'remains under thez'manual control of the-operatorsat.tlie. A operatorpositions," rendering the number of 'calls on thetelephone linesfanswered by' anioper'ator at a given A operator position`and. routed therefrom tothe Boperator `positions to 'be completedentirely within the discretion of` the operator attlie given A operatorposition.

Accordinglyitis an object ofthe present invention toprov'i'de inaitelephonesystem f Vthe type deScribedVimpoved `apparatus .fordistribting calls -on telephone lines to "a number of A.operatorrpositions to be answered.

vAnother"object of the invention 'isl to iprovide in a telephone systemincluding anumbe of A operator :Lp'ositionsiand .a numberof..Boperatorpositionsgan `improved arrangement for fdistributingincoming calls on telephone lin'es'to` the Aoperatorpositions toi beanswered.` and.' for distributing 1 recalls on established connectionsto the Aoperatorlpositions to be answered.

Another i object `of `.the invention 'is'V to provide in a telephone`:system including a number of A operator "positions and va .number ofBoperator positions and apparatus under` .the control ing recalls on theestablished connections to- -the -A operator positions to :be answeredand `for .governing coin Acollection V and i refund "mechanism andmessage re'gistermechanism associated with the telephone lines.

-A'furthery object of jthe A invention'is to i provide in `a telephonersystem including an operator position provided with facilities -for"answering 4a callback'upon-an established-connection,improvedswitcliing lapparatus included -in the establish'ed connection'and embodying control apparatus selectively 'governable over thel estab-'lished connection forjcreating-agcall-back upon .the-establishedconnection rand for governing coin-col-lectionand refund mechanism oryrnes- `sagere'gister mechanism associated witha* calling line 'includedin theestablished connection. The features ofV the present invention are4illustrated .as being incorporated in -atelephone system comprising anexchange terminating v a apluralityof manual telephone lines andincludring -anumberjof Aoperator'positions; a numiber of B "operatorvpositionsand a number of switching links.A The switching links-haveacfcfess to Vthegltelephone lines, Vto the A operator .positions-anditothe Bioperatorfpositions; while the B operator positions have access tothe' tele- :phone'linesp The ltelephone lines comprisetwo `classesvvhich'are i rendered correspondingI classes of servioe consisting f ofYmessage. register service :lo and prep-ay*service.` c. i

' In accordance with; one feature'4 of the invention, thetelephonesystemcomprises aplura'lity` of telephone lines, a i plurality; of VA operator-positi'ons andfsa Bf operator jposition.V -Also thegli-system-compris'es"means for-1outing'a call on -any-one of .thetelephone 'lines to an idle-one of thel 'A'folserator positions to beanswered, vmeans" for routing `a call from the one A'oper- 1atorposition to Ithe -B operator position, and

o means for` establishing a connection between' the fonetelephone -line`and 'the -B operator position "-indepennent `of the one A operatorposition,

` -thereby to route acallfromgthecne telephone line to the B operatorposition- V Furtheruthe system comprises `means for routing a recall byparticularly, the "system comprises Va switchingA 5o `.link including ananswer switch fhaving l'access to the telephone lines, va nderswitchhaving za'ccessto the A operator positions and a call s'witcnhavingaccess to the 'B operator VApositions, and lmeans controlled i by 4thepresence `of a callionone .ofthetelephone lines forinitiating operationsof the answer switch and the nder switch of the switching link, theoperation of the answer switch being arrested when it finds a callingone of the telephone lines and the operation of the finder switch beingarrested when it finds an idle one of the A operator positions. Also,each one of the A operator positions has an identity unit individuallyassociated therewith which is controllable from the one A operatorposition to indicate the particular character identifying a callingtelephone line seized by the finder switch of the link, each of thetelephone lines being identified by a particular multi-symbol character.

In accordance with a further feature of the invention, in the telephonesystem, each switching link comprises control apparatus which isoperative in a first manner to create a call-back upon an establishedconnection including a calling first line extending to a paystation or acalling second line extending to a substation and a called third line,and operative in a second manner to release the link. Also thearrangement comprises means controllable over the third line forselectively governing the manner of operation of the control apparatus,means for routing a call-back upon the established connection to anoperator position to be answered, additional means operative under thecontrol of an operator at the operator position for releasing the link,means operative under the control lof an operator at the operatorposition for governing coin collection and refund control means to causecoins deposited in a coin receiving means at the paystation to berefunded in the event the first line is included in the establishedconnection, and additional means controlled only in response to therelease of the link by the control apparatus for governing the coincollection and refund control means to cause coins deposited in the coinreceiving means to be collected in the event the first line is includedin the established connection and for operating a message registerassociated with the second line in the event the second line is includedin the established connection.

Further features of the invention pertain to the particular arrangementof the circuit elements thereof, whereby the above-outlined andadditional operating features are attained.

The novel features believed to be characteristic of the invention, bothas to its organization and method of operation, together with furtherobjects and advantages thereof, will best be understood by reference tothe following speciiication taken in connection with the accompanyingdrawings in which Figure 1 illustrates the general arrangement of atelephone system including a local exchange and a distant exchangeembodying the present invention; and Figs. 2 to 7, inclusive, whencombined in the manner shown in Fig. 8, illust/rate the details of asystem having incorporated therein the features of the invention, asbrieiiy outlined above.

Description of the apparatus incorporated in the telephone systemReferring now more particularly to Fig. 1 of the drawings the telephonesystem there illustrated comprises a local exchange 28, a distantexchange 3l) and a plurality of one-way trunk lines, including the trunkline 410, extending therebetween. The local exchange 20 and the distantexchange 30 are of the manual type, each serving a number of groups oftelephone stations to which `different classes of service are rendered.For example, the local exchange 20 serves a group of subscribersubstations, including the subscriber substation Tl, which is `renderedmessage rate register service; and a group of paystations, including thepaystation T2, which is rendered prepay service. A telephone line havinga line circuit individually associated therewith extends to eachtelephone station in the local exchange; the telephone lines 265 and245, respectively, extend to the subscriber substation Tl and to thepaystation T2. Also, it is noted that each telephone line in the localexchange 20 is identified by a particular multi-symbol characterconstituting a directory number in a manner more fully explainedsubsequently. The message rate line circuit 200 is individuallyassociated with the telephone line 205; and the prepay line circuit 240is individually associated with the telephone line 245. Each of thesubscriber substations and paystations in the local exchange 20 isprovided with station equipment including a telephone instrument and aringer.

Further each of the paystations is provided with mechanism for receivingcoins or the like and apparatus for controlling collection and refund ofcoins deposited in the coin receiving mechanism, which may beconstructed and arranged in the manner shown and described in Oscar F.Forsberg Patent No. 1,043,219, issued November 5, 1912.

Also the local exchange 29 comprises a number of A operator positions,including the first A operation position 500, and a number of B operatorpositions, including the first B operator position 484. Also a group oftoll lines, including the toll line 499, terminates at the localexchange 2i) and extends to a remote exchange, not shown. Each Aoperator position has a trunk individually extending thereto, the trunk528 individually extending to the first A operator position '560; andeach B operator position has a group of trunks individually extendingthereto, the trunk 490 being included in the group of trunksindividually extending to the first B operator position 494. Each trunkextending to each B operator position is provided with a trunk linecircuit individual thereto, the trunk line circuit 445 being individualto the trunk line 49) extending to the first B operator position 494.Each toll line terminated at the local exchange 2li is provided With atoll line circuit individual thereto, the toll line circuit 491 beingindividual to the toll line 499. Also each trunk line extending betweenthe local exchange 29 and the B operator position 498 in the distantexchange 30 is provided with a trunk line circuit individual thereto,the trunk line circuit 412 being individual to the trunk line 410extending between the local exchange 20 and the B operator position 498in the distant exchange 39.

Further the local exchange 2l! comprises a number of finder-selectorlinks, including the finder-selector link illustrated, and a linkdistributor 30| for assigning idle ones of the links to the use of thetelephone stations. For example, the link illustrated includes a finderswitch 330 and a selector switch 439. Also a sequence switch isindividually associated with each of the links, the sequence switch 380being individually associated with the link illustrated. Further thelocal exchange 20 comprises a main A operator position distributor B30and an auxiliary A operator position distributor 695, each of the Aassensoo'perator positiondistributors beingV operative Ato assignidleones of! the- AK operatory positions to receive incoming calls orrecalls to the local exchangeA 20 in a-predetermined order- Finally thelocal exchange 20-` comprises a call storage-unit w `and anumber ofidentity units individually associated with theY A. operator positions,the first identity unit libeingindividually associ-` ated withthefirst-A operator positionl Eachoflthe finder switches, such, for example, as.the finder switch3ll0, constitutes an answer switchl having access.to.each-of the telephone lines .in the local exchange.; each oftheselector switches, such, forexample, as the selector switch itil.;constitutes a. call. switchfhaving access to eachof the trunkscextendingto .the Boperator. positions andto the` toll.lines and .to `each ofthetrunk` lines; extending., tothe distant exchange 3B.; andeachof thesequence switches, such, for example, asthesequence. switch 380,constitutes a positionandlstorage` finder switch having access toeach ofthe trunks individually extending to the. Apperatorpositions. and .tothecall storage unit S. Also it is noted that each B operator position inthe local exchange 2E has` access to each .telephone4 linev therein.

The distant exchange 33 comprises a number of A operator positions, notshown, and a number of B operator positions including the B operatorposition 438, previously mentioned. It is noted that the trunk line4.1i) extending between the local exchange 2|)v and the distant exchangeSliis terminated at the B operator position lied in the distant exchange3i).

Preferably, each of the lnder-selector links is identicalto the linkillustrated which comprises a iinder switchSil anda selector switchlifll, as previouslynoted. The finder switch 365, as best shown in Fig.3, comprises a switching mechanism 3H! of the 20D-point Strowger typeincluding a carriage provided with a first wiper set, including thewipers 3M, 3I5 and 3|5, a second wiper set including the wipers 3| I,3|2 and 3|3 and a control wiper 3H.

wipers 3| I, 3I2 and 3|3 of the second wiper set are capable of bothVertical and rotary movements; while the control wiper 3|l' is capableof vertical movement. Further the mechanism 3H) comprises acircumferentially disposed `main conu tact bank provided with twosections respectively associated with the first and second wiper setsand a vertical control contact bank associated with the control wiper3|1. Accordingly, in the mechanism 3|il, the rst and second wiper setsrespectively have access to the first and second groups of one hundredlines each, respectively terminated by the first and second sections ofthe main contact bank. Also the mechanism 3H) is provided with avertical magnet M365 for moving the iirst and second wiper sets thereofin the Vertical direction, a rotary magnet M361 for moving the first andsecond wiper sets thereof in the rotary direction and a release magnetM339 for releasing the rst and second wiper sets thereof and for causingthese wiper sets to be returned to their normal positions. Finally, themechanism 3|0 has two sets of switch springs S352 and S356 operativelyassociated'therewith, which are controlled in accordance with themovements of the first and second wiper sets thereof, in a manner morefully described subsequently.

Also the nder switch 300 comprises a number of relays including twoswitching relays R320 and R330, a startrelay R340, a stop relay R350, an

It is noted that the wipers 3|4, SI5 and 346 of the first wiper set andthe identity relay R301and aout-in relay-,R313 connected' and arranged;ina.- manner more fully` described hereinafter.`

The selectos switchil, as bestshownin Fig.. 4, comprisesa-switchingmechanism 4100i the point Strowger type including a .carriage .providedwitha vwiper set includingthe wipers 4| I, 4 2 and M3. Itis notedthatthewipersi I, M2 and4|3 of the-wiper sets-are capable ofbothvertical and rotary movements. Further. the .mechanism i I i) comprisesa.circumferentially.disposed maincon-Y tactbank associated: withthe.wiper` set. Accordingly, the wiper. setthas aocessto a group. of onehundred. lines terminated` by. the contact bank. Also the mechanismA IUilisprovided .with a vertical magnet ,MMA for moving the` wiper setthereoffin the. vertical direction, arotarymagnet M418.. for. movingthewiper.. set thereof in the rotary direction, and areleasev magnetMlilfor releasing the wiper setrthereof and forV causing the wiper settobe returnedto itsynormal position. Finally the mechanism 4| has anumber of switch springsSIS, S42,.,Sfl2|S422, Sf-i23 andzSsi/`operatively associated therewith, which are `controlled in accordancewith `the movements of the wiperset thereof, ,inf a manner more fullydescribed subsequently.

Also the selector switch .4M comprises anumber ofrelays includingv acontrol relay RME, a coin and register relay R43|la call pack` relayRfi, twoholdrelays R445; and R480, 4aline relay R453, a switch-.throughrelay Rlha battery supply relay Rolo, atransfer relay R485 and aswitching relay Riso connected-aand, arranged in a manner more fullydescribedsubsequently.

Preferably, each of the sequenceswitches is identical to the sequenceswitch 33E! individually associated with the link illustrated. Thesequence switch 3.8i! is of the rotary type and comprises, as best shownin Fig. 3, six rotary wipers Sti, 383, 3&5, 337, 339 and 39| providedwith individually associated rotary contact banks 382, 33d, 3%, 383, 3%and 392. Also the sequence switch 339 is provided with a rotary magnetM393 for moving the wipers noted in the rotary direction.

Thelink distributor 39| illustrated in Fig. 3 has;` access to each ofthe links in the local exchange 2S and is operative to assign an idleone of the links to the use of any one of the telephone stations in thelocal exchange` 2i). The details of the connection and arrangement ofthe link distributor 30| are not disclosed as they form no part of thepresent invention. However, for reference purpose, it is noted rthat theconnection and arrangement of a link distributor of the type of the linkdistributor 30| is shown in the copending application of Edward S.Peterson, Serial No. 233,021, filed October 3, 1938. Also a markingnetwork 283, shown inFig 2, is associated with the link distributor Sill`in order to initiate operation thereof when a call is initiated on oneof the telephone lines extending to a telephone station inzthe localexchange 2li. Also the marking network 283 comprises a busy relay R285;associatedwith the link distributor Sill and a tone transformer 29Dcommonly associated with the various line circuits, in a manner morefully described hereinafter. i

Preferably, each of the message rate line circuits is identical to themessagey rate line circuit 230 individually associated-with thetelephone line 265 extending to the subscriber substation TI, shown inFig. 2, which .comprises a line relay RMO, a cutoff relay R220. andalockoutrelay R230 connected and arranged in a manner more fullydescribed subsequently. Also, a signal lamp LZES and a message registerprovided with an operating magnet M211 is individually associated withthe message rate line circuit 200.

Preferably, each of the prepay line circuits is identical to the prepayline circuit 240 individually associated with the telephone line 245extending to the paystation T2, shown in Fig. 2. The prepay line circuit240 comprises a line relay R250, a cutoi relay R260 and a lockout relayR210 connected and arranged in a manner more fully describedsubsequently. Also a signal lamp L268 is individually associated withthe prepay line circuit 240.

Preferably, each of the trunk line circuits is identical to the trunkline circuit 405 individually associated with the trunk line 490extending to the first B operator position 494, shown in Fig. 4, whichcomprises a line relay R401 and a busy relay R463 connected and arrangedin a manner more fully described subsequently.

Preferably, each of the B operator positions in the local exchange 20 isidentical to the first B operator position 494, shown in Figs. 4 and 2.The first B operator position 494 comprises conventional answeringequipment, not shown; conventional calling equipment including a numberof call jacks J20l and J202 respectively terminating the telephone lines205 and 245; and a number of conventional cord circuits, not shown.

Preferably, each f the A operator positions is substantially identicalto the first A operator position 500, shown in Fig. 5, which comprises atrunk circuit provided with a set of position keys including a refundkey K565, an error release key K510, an identity key K515, a trunkdisconnect key K580 and an A operator position distributor key K590.Also the trunk circuit at the first A operator position 500 comprisestelephone apparatus 5I1 including the usual telephone instrument andrepeater, not shown, a retarder coil 530, a key sender K520, and anumber of relays including three tone relays R5I0, R520 and R525, arefund relay R530, a send relay R540, an error relay R535, a disconnectrelay R550, an answer relay R545 and a busy relay R560. Also associatedwith the first A operator position 500 are a peg count meter providedwith a register magnet M548 and an identity lamp L583. The key senderK520 is of a well-known type; accordingly, the details of the connectionand arrangement thereof are not disclosed as they form no part of thepresent invention.

As previously noted, the other A operator positions are substantiallyidentical to the iirst A operator position 500, and the other A operatorpositions being different from the first A operator position 500 in thatthey do not include an A operator position distributor key and a busyrelay, as only the first A operator position 500 includes thisapparatus.

The call storage unit 600, shown in Fig. 6, comprises six marking relaysIM to 6M, inclusive, a control relay R6i0 and a release relay R620connected and arranged in a manner more fully described subsequently.Also, six storage lamps Lll to L606, inclusive, are associated with thecall storage unit 600 and commonly associated with each of the Aoperator positions.

Preferably, both the main A operator position distributor 630 and theauxiliary A operator position distributor 695 are identical; the main Aoperator position distributor 630 comprising,

as shown in Fig. 6, a hold relay R610 and a number of position relaysR630, R640, R650, etc., respectively corresponding to the various Aoperator positions, connected and arranged in a manner more fullydescribed subsequently.

Preferably, each of the identity units is identical to the rst identityunit individually associated with the first A operator position 500which comprises, as shown in Fig. '1, a first test switch 'H0individually associated with the rst group of one hundred linesaccessible to the finder-selector links associated with the first Aoperator position 500; and a second test switch, not shown, individuallyassociated with the second group of one hundred lines vaccessible to thefinder-selector links associated with the first A operator position 500.The test switch 1I0 is of the rotary type and comprises six rotaryWipers "III, H3, 1I5, 1I1, 1l9 and 12| provided with individuallyassociated rotary contact banks 112, "H4, H6, 118, and 122. Also thetest switch 'Ht is provided with a rotary magnet M123 for moving thewipers noted in the rotary direction.

Further, the first identity unit "il comprises a iirst start relay R anda first stop relay R140 individually associated with the first testswitch and a second start relay and a second stop relay, not shown,individually associated with the second test switch. Also the firstidentity unit includes a test transfonner 155, a lockout relay R'i, aswitching relay R160, five testing relays l'ZU, SMU, 56U`, 16U and @0Uand ten marking relays iD to 10D, inclusive. Finally, the first identityunit W0 comprises a group of identity lamps including a thousand-digitlamp MLI, two hundred-digit lamps CLI and CL2, ten tendigit lamps DLI toDLli, inclusive, and ten unit-digit lamps ULi to ULM?, inclusive. Thefirst identity unit 'E63 is so connected and arranged that, when theidentity key X515 at the first A operator position 595 is operated, therst identity unit 160 operates in a manner more fully describedhereinafter, thereby to cause the four of the identity lamps to beilluminated which correspond to the directory number of the line seizedby the iinder switch of the finder-selector link associated with thefirst A operator position 500.

A better understanding of the connection and arrangement of theapparatus incorporated in the telephone system will be facilitated froma consideration of the detailed operation of the various pieces ofapparatus incorporated therein incident to the completion and handlingof the various calls at the first A operator position 500, as willappear hereinafter.

General operation of the system Considering now the general operation ofthe system with reference to Fig. l of the drawings, it is noted that,when a call is initiated at any one of the subscriber substations or atany one of the paystations in the local exchange 20, the line circuitindividually associated with the telephone line extending thereto iscontrolled, thereby t0 initiate operation of the link distributor 35|.The link distributor 36! is of the preselective type and operates toselect an idle one of the links when a previously selected link isassigned to the use of a calling telephone station. Accordingly, thelink distributor 30! operates at this time in order to assign apreviously selected one of the links, such, for example, as the linkillustrated, .to the use of the calling tele* phone station; whereuponthe nder switch 306 thereof operates to seize the telephone line extending to the callingtelephone station, andoperation of the sequencelSwitch Sindividually associated with the link illustrated is initiated.When the nder switch 300 seizes the telephone line extending to-thecalling telephone station, such, for example, asthe telephone line2Ii5'extending to the subscriber substation'll, the link distributorStil is releasedV and operatesto pre-` select another idle link, aspreviously. noted.

TheiA operator position distributor 33t preselects one of the idleAoperator positions for use; and when a preselected one ofv theAoperator positions is taken for use the A operator position distributorE30 operates to. preselect another idle one of the A operatorpositionsfor use. Upon operating, the sequence switch 33S seizes thetrunk extending to the previously selected A operator position, such,for example, as the trunk 520` extending to the first A operatorposition de, thereby-to extend the call from the calling subscribersubstation Tl tothe selected first A operator position 59B. The operatorat the rst A operator position 5to answers'the call andthen operates thekey sender ather position, thereby to control the operation of theselector switch liet in order to extend the call to its destination. Inthis connection it is noted that the selector switch 453i) maybeselectively conH trolled to extend the call to any idle B operatorposition in the localexchange 20, to the B operator position 49% in thedistant exchange 3! or over a toll line, such,. forv example, as thetoll line i599.

In the event the call is to be routed to a telephone station inthe localexchange Zi, the selecto;` switchlll is controlledin order to route thecall to an idle B operator` position inthe local exchange 2Q. Theoperator` atA the idle B operator position in the local exchange 23answers the call and then extends the call to the called telephonestationv in the local exchange 2i), in the usual manner. In the eventthe call is to be routed to a telephone station in the distant`exchange-Sil, the selector switch 4&8 is controlled in order to routethe call totheB operator position i313` in the' distant exchange 3Q. The.operator at the Bi operator position 498 in the distant exchange 3Qanswers the call and then extends the call to the called telephonestation in the distant exchange. in the usual manner. In the event thecall is to be Arouted toll, the selector switch 45H3 is controlled inorder to route the call to an` idle one of the toll lines, such, forexample, as the toll line tti); Thereafter the call is further extendedover the toll line to its destination in the usual manner.

After the call has been routed from the iirst A operator position 5G!!in the local exchange 2G to an idle one of the B operator positions inthe localexchange 2i), to the B operator position A498 in the distantexchange 3i! or over one of the tolllines, and the informationconcerningthe extension of the call has been conveyed to the called operator, theoperator at thev rst A operator position 5M releases the connectionbetween her position and the ynder-selector link, whereupon a directconnection is completed between the finder switch and the selectorswitchl of the link excluding the rst A operator position Beil.

It is not that the called operator at a B operatcr position in the localexchange Eil or `at the B operator position 498 in the distant exchangeSil, to which the call is routed-by the selector switcl 400, may recallthe operator at an idle one o'EV the A operator positions in the localexchange 20v by causing the sequence switch 380 individually associatedwith the link illustrated to seize the trunk extending to the idle Aoperator position under the control of the A operator positiondistributor 630, in the manner previously explained.

It is noted that the selector switch 400 comprises apparatus which is soconnected and arranged that, when the connection is released, the chargefor the call is made automatically. More particularly, in the event theconnection includes a telephone line in the local exchange 20 renderedmessage register service, the message register in the line circuitassociated with the telephone line is operated in order to register acall; on the other hand, in the eventY the connection includes atelephone line in the local exchange 2i) rendered prepay4 service, thecoin collect and refund mechanism at the paystation associated with thetelephone line is automatically controlled to collect the coin depositedtherein. Also the coin collect and refund mechanism at apaystationassociated with a line included in a con-- nection may be controlledfrom the-rst A operator position 500, thereby to causeit to, refund thecoin deposited, therein.

Also itis noted that, when a connection. is routed to the first Aoperator position 50E),l the operator thereat may initiateoperation ofthe rst identity unit 10i), thereby'to cause the firstv identity unit'l'llilV to operate. andidentify the directory number of the callingtelephone line in the local exchange 2.0 includedin the connection, asdetermined-by the operation of the nder switch 300 of theplink.illustrated. to seizethe calling telephone linein the localexchange 20.

In'the event all of` the` A operator positions in the local-exchange 20are busy when operation of the seque-nce switchli).` is initiated, thesequence switch 38|] seizes the call storage unit 60B. Moreparticularly, the sequence switches` individually associated with thelinks inthe local exchange 20 seize the respective positions of the callstorage unit lill()k in a predetermined order, thereby to cause thecalls and recalls to be stored in the call storage unit 600 in apredetermined order when all of the A operator. positions inthe localexchange 20-are busy. At this time,` when a number of calls andrecalls--ona number of the links are stored in the callstorage unit E00and one of the A- operator positionsin thelocal exchange 20 `becomesidle, the A operator position distributor 63E! operates to assign theidle A operator position for use and causes ythe callstorage unit M9 toinitiate operation of the sequence switch corresponding to the-firststored call or recall in the call storage unit 603. The sequence switchcorresponding to the first storedV callV or recall in the call storageunit 60E) 'then operates to rind the assigned A operator position. Thecall storage unit 609 then operates-to causeeach of the remainder of thesequenceA switches to be advanced one position, thereby tov advance,` byone position, thecalls and recalls stored in the call storage unit-600.Accordingly, the call storage unit Gill) operates to cause incomingcalls and recalls to be stored in a predetermined order when allof the Aoperatorpositions in the local exchange 20 are busy; and causes thestored calls and recalls to be released to be answered at the A operatorpositions in the same predetermined order as the A operator positions inthe local exchange 2i) become idle.

After'a call from a calling telephone station has been extended from one.of the A operator positions to one ofthe B operatorV positions ineither the locall exchange or the distant exchange 30, the release-ofthe established connection is primarily under the control of theoperator at the calledoperator position. On the other hand, afterY acallfrom a calling telephone station has been extended from one of the AoperatorA positions to a toll line, the release of the establishedconnection is under the joint control of the calling telephone stationand a toll operator position associated with the toll line.

` Message rate subscriber substation call A call from a message ratesubscriber substation, such, for example, as the subscriber substationTI, is initiated by removing the receiver of the telephone instrumentthereat from its associated switchhook. AWhen the receiver of thetelephone instrumentat the subscriber substation TI Vis removed from itsassociated switchhook, a bridgepath is completed between the lineconductorsCZE'and C201of the telephone line 205V extending tothesubscriber substation TI. When this bridge path is completed betweenthe line conductors ofthe telephone line 205, a circuit is completedfor, energizing in series the upper and Ylower windings of the line.relay R2|0;Y This circuit extends from ground by way of the contacts281, C294, the lower winding of R2|0, the contacts 222, C201, the bridgepath between the. line conductors C201 and C206 at the subscribersubstation T|, C206, theY contacts 22| and the upperwinding of R2|0 tobattery. When energizedoverthe above-traced circuit the line relay R2|0operates to complete, at the contacts. 2 |73, Van Vobvious path forapplying ground potential to the control conductor C209 of the telephoneline Y20,5 terminating in the `iack .120|

at the first B operator position 494, thereby to I ing of the cutoffrelay R220 to the control conductor C208 of the telephone line 205,thereby to mark the telephone line 205 as a calling line to the nderswitches having access thereto. Furtherthe line relay R2|0 completes, atthe contacts 2||, a path for applying resistance ground potential to thestart conductor C-8 extending tothe link distributor 30|, this pathextending from ground by way of the contacts 2|| and 23|, C283, theresistor 282 and the contacts 288 to the start conductor C308. Also theline relay R2|0 completes, at the contacts 2||, an obviouspath forapplying direct ground potential by way of the marking conductor C283 tothe rst contacts in the vertical control contact banks of the nderswitches. The application of resistance ground potential to the startconductor C308 initiates operation of the link distributor 30|; and theapplication of direct ground potential to the rst contacts in thevertical control contact banks of the iinder switches marks thetelephone line 205 as terminating in the first level of the main contactbanks of the i'lnder switches.

The link distributor 30| is of the preselective type and operates toselect another idle link as soon as the nder switch of a previouslyselected link operates to find a calling telephone line after it hasbeen taken for use. Assuming that the link distributor 30| haspreviously selected the link illustrated to be taken for use at thistime, the link distributor 30| operates to cause ground potential to beapplied to the start conductor C392, thereby to complete an obviouscircuit for energizing the winding of the start relay R340 in the finderswitch 300 of the link illustrated. The start relay R340 then operatesto interrupt, at the contacts 346, a point in a multiple path forapplying ground potential to the all-link-busy conductor C309 and tocomplete, at the contacts 34|, an obvious path for applying groundpotential to the control conductor C364 of the trunk 360. The previouslymentioned path for applying ground potential to the all-link-busyconductor C309 in the finder switch 300 extends, when completed, fromground by way of the contacts 346 and the contacts 358 of the set ofswitch springs S356 to the all-link-busy conductor C309. Also the startrelay R340 prepares, at the contacts 34|, obvious multiple circuits forenergizing the lower windings of the switching relays R320 and R330,prepares, at the contacts 345, a circuit traced hereinafter forenergizing the vertical magnet M365, and prepares, at the contacts 344,a circuit traced hereinafter for energizing the rotary magnet M361.

The link distributor 30| then operates to cause ground potential to beapplied to the vertical conductor C305, thereby to complete thepreviously mentioned circuit for energizing the vertical magnet M365,this circuit extending from the grounded vertical conductor C305 by wayof the contacts 345 and the vertical magnet M365 to battery. Whenenergized over the abovetraced circuit the vertical magnet M365 operatesto drive the rst and second wiper sets of the mechanism 3|0 one step inthe Vertical direction and to complete, at the contacts 366, an obviouspath for applying ground potential to the interrupter conductor C306.The application of ground potential to the interruptor conductor C306causes the link distributor 30| to interrupt the application of groundpotential to the vertical conductor C305; whereupon the vertical magnetM305 restores to interrupt, at the contacts 366, the previouslymentioned path for applying ground potential to the interruptorconductor C306. Accordingly, the vertical magnet M365 operatesintermittently, thereby to drive the first and second wiper sets of themechanism 3|0 step by step in the vertical direction until the controlwiper 3|1 engages a Contact in the associated vertical control contactbank having direct ground potential thereon; whereupon an obvious pathis completed for applying ground potential to the test conductor C301extending to the link distributor 30|. In the present instance, thefirst and second wiper sets of the mechanism 3|0 are driven only onestep in the vertical direction; whereupon the vertical control wiper 3|1engag-es the first contact in the associated vertical control contactbank having ground potential thereon. The application of groundpotential to the test conductor C301 causes the link distributor 30| tooperate, thereby to interrupt the application of ground potential to thevertical conductor C305 and to applygrcund potential to the rotaryconductor C304.

The application of ground potential to the rotary conductor C304completes the previously mentioned .circuit for energizing the 'rotary4magnet M361, .this circuit extending "from lthe grounded rotaryvconductor C304 4by Way `of the contacts344, :336 and` 328 and'therotarymagnet M361 to battery. When energized `over the `above-traced.circuit the rotary magnet "M361 operatesto drive the first andsecond`wipersets o'flthe mechanism3 |10 one step Aintherotaryfdirection-andito complete, at Ithe contacts A366,an

`obvious path for applying ground .potential to the interrupt-erl.conductorC366- 'This applica- Vtionof ground potential'toitheinterrupter-conductor C366 causes the `link -distributor 130| tooperatel and removethefapplication o'f ground potential -to 'the vrotaryconductor C304; whereupon the rotary Y.magnet M361 yrestores tofinterrupt,

at the contacts 366, the 'previously 'mentioned path for applyingAground `potential to the interrupter 4conductor C366. Accordingly, therotary ymagnet M361 operates intermittently, thereby to driveftherstandsecond wiper sets'of the mechanism -3 I 6- step bystep infthe rotarydirection until either the control wiper "316 or the `control Wiper "3 3of the respective first and second wiper conductor ofy acallingtelephoneline having bat- `tery lpotential thereon.

Inthe present example,thetelephonefline 265 is'includedinthe firstsection of -the main contact bank-ofithe mechanism `316. Accordingly,when C the-control wiper i6 of the rst wiper set ofthe mechanism`3|`6engages the contact of the'contact set in the first-section of the mainContact bank of the-mechanism3l0 Vterminating the control conductor C268of lthe telephone line 1205, a circuit is completed Zfor energizing `theupper winding of the switching relay R336. This circuit extends from thegrounded marking "conductor C263 gbylway ofthe -vertical'control wiper 3I1 of the `mechanism 3|6, the upper winding of R330, thecontacts-324 andthe control wiper 3|6 of the iirst wiper set of the mechanism 3|0 to thecontrol conductor C206 of the telephone'line 265, the vcontrol conductorC268of thetelephone `line 5265 -h'aving battery potential thereon. Whenltion due to vrthehigh series resistance of this holding circuit.Accordingly, further operation `of the mechanism -3|6 is arrested. -Alsothe switching relay R330interrupts, atthecontacts 334, `a'point in anobvious circuit for energizing the upper Winding of the switching relayR326, thereby positively to prevent operation of the latter relay atthis time. 'Further the switching relay R336 interrupts, atthecontactsl339, a point in a circuit 'traced hereinafter for energizing therelease magnetMB-S and completes,at the contacts 336, a connectionbetween the rotaryconductor C364 `and the .guard conductor "C363, thisconnection extending 'from vthe rotary conductor C304 by `way of thecontacts i344, 336 and r34'2 to theguard conductor C303. When the rotaryconductor C364 Lis connected to fthe guard `conductor-C363,

'sets engages a contact terminating the-control `125 `signal "lamp L2|56.

Ioperation `of fthe link :distributor .36| to 'control the finder switchi366 istarrested,"whereupon the `link distributor 36| operatesautomaticallyto select foruse Lanotheridle ione of the links.

'Alsolit is 'noted that, Awhenrthe carriageof the lmechanism 1'3`|0 isdriven onestep .in the Verti- .caldirection, the setsorswitch springsS352 and C356 4are actuated. `More.partic1'ilarly,the"con- `tacts '35'1.and`358 of lthe set ofswitch springs rS356 are yactuated. respectivelyinto engagement land disengagement, thereby to prepare a Vfurther pointinthe .previously mentioned circuit `for energizing "the lrelease`magnet M369 and 'to interrupt afurther point in the .previouslyitrace'dpath for applyingground potential in the nder switch ,3`0`0`rto theall-link-.busy conductorC309. "Finally, `the `contacts 364 and 353 of`the setfof switch springsS352 are 'actuated respectively intoAdisengagement "and engagement, thereby to interrup't the connectionbetweenthe controlconductor C364 of thetrunk 366 andthe guard conduc-`tor C363land to vprepare a `path traced .hereina'fterfor applyingground potential to `the guard lconductor C363. Finally, uponfoperating, the

'switching relay 'R330 completes, at the contacts 33|, 332 and'333,.connections`between the conductors of the trunk360 extendingbetween the iinderr switch 366 andthe selector switch 466 v and.thei'irst wiper seto'fithe mechanism 316. More particularly, a circuitisfcorn'pleted, at the convtacts 333, for energizing-the windingoflthecutoi relay R220, this rcircuit extending from the grounded controlconductor C364 di the trunk the wiper 3|6, the=control conductorC268-off the A telephone line 205, thecontacts'/ZIIZ and i236 yand thewinding of R226to` battery. When-the winding of `the cutoff relayR220-is thus energized this relay operates toin'terrupt at the contacts4225, the `previously meritionedpath for applying lbattery potential by-Waycf `'the resistor 2|6 to the control conductor l'C266 -fof thetelephone "line 265 and-to complete, at the contacts v224, `a holdingvcircuit for energizing the Winding of the cutoff relay R220, thisyholding circuit extending from the grounded control-conductorCZfS ofthe telephone line l265 by-way of Ethe contacts A'224 and vthe winding0612.226 Ate battery. Also the cutoil relay'R226 interrupts, atthecontacts "226, a point in an obvious circuit 1for illuminating thevsignal lamp L2 |8an`d completes,fat the contacts 223, an obviouscircuit :for energizingthe winding ofthe lockout relay R236, therebyl"to cause the Llatter relay to operate. Finally, -theoutoi relay R226interruptsyat the contacts I2| and 222 the previously 'traced circuit`for `energizing .the .winding of theline relay R2l0, .thereby to `clearthe tele- ,phone line 265 of impedance ,elements and to cause .thelatter relay to restore.

,Upon operating, the .lockout Jrelay R233 .pre-

pares, at `the contacts 232,-a pointua holding `circuit tracedthereinafter' tfor energizing the winding thereof, completes, Vatthecc-ntacts 233,

.-an obvious alternative path for'applying ground potential `to `thecontrol conductor `C266 of 'the telephone line 205,'thereby'to'markthetelephone -line 265 .as-busy .tothefB operator positions inthe ilocalexchange A26 havingaccessthereto.'and prefpares, at the contacts 235, a`further point .in the previously mentioned -circuit for lillurninatingthe Upon restoring, the line relay R2|`6 interrupts, at the contacts 2H,the previously A'traced 'paths for lapplying direct `ground c potentialto the Vmarking conductor 4C263 and Yresistance ground potential to thestart conductor C306 extending to the link distributor 30|.

Further it is noted that the link distributor 30| operates in order toselect another idle link for use only in the event ground potentialappears upon the all-link-busy conductor C309 in the finder switch of atleast one of the links, groundv potential being removed from thealllink-busy conductor C309 in the inder switch 300 of the linkillustrated at this time, due to the operated condition of the set ofswitch springs S356, as previously noted. Also, at this time, groundpotential is applied to the guard conductor C303 in the finder switch300, thereby to prevent the link distributor 39| from preselecting thelink illustrated due to the busy condition of this link. The path forapplying ground potential in the finder switch 300 to the guardconductor C303 extends from ground by way of the contacts 353 of the setof switch springs S352 and the contacts 343 to the guard conductor C303,the start relay R340 being restored at this time. Further it is notedthat the start relay R340 is of the slow-to-release type and restoresshortly after the link distributor 30| is released. Upon restoring, thestart relay R340 interrupts, at the contacts 34|, the previously tracedpath for applying ground potential to the control conductor C364 of thetrunk 360, ground potential being applied to the control conductor C364of the trunk 350 in the selector switch 400 at this time. Further thestart relay R340 interrupts, at the contacts 344 and 345, additionalpoints in the previously traced circuits for respectively energizing therotary Vmagnet M361 and the vertical magnet M395.

However, the previously traced holding circuit for energizing the rotarymagnet M361 and the lower winding of the switching relay R330 in seriesis retained completed, due to the presence of ground potential upon thecontrol conductor C364 of the trunk 369 in the selector switch 400 atthis time.

When the trunk 350 is connected to the telephone line 205 due to theoperation of the switching relay R330 in the finder switch 300, a loopcircuit is completed for energizing in series the upper and lowerwindings of the line relay R450 in the selector switch 400. This circuitextends from ground by way of the lower winding of R450, the contacts466, 433 and 423, C362, the contacts 316 and 332, and the wiper 3| 5 tothe line conductor C201 of the telephone line 295, and from battery byway of the upper winding of R450, the contacts 463, 43| and 426, 030|,the contacts 313 and 33| and the wiper 3|4 to the line conductor C206 ofthe telephone line 205, the

line conductors C206 and C201 of the telephoneA line 295 being connectedtogether by way of the bridge path at the subscriber substation Tl, Whenthe upper and lower windings of the line relay R450 are thus energizedthis relay operates to complete, at the contacts 453 and 45|, an obviouscircuit for energizing the winding of the hold relay R480, thereby tocause the latter relay to operate. Upon operating, the hold relay R480completes, at the contacts 403, the previously mentioned path forapplying ground potential to the control conductor C364 of the trunk360, as previously noted. Also the hold relay R400 completes, at thecontacts 48|, an obvious circuit for energizing the upper winding of theswitching relay R490, thereby to render the latter relay exceedinglyfast to operate when the lower winding thereof is subsequentlyenergized. Further the hold relay R480 prepares, at the contacts 432, apoint in a circuit traced hereinafter for energizing the lower windingof the switching relay R460 and prepares, at the contacts 484, a circuittraced hereinafter for energizing in multiple the lower winding of thetransfer relay R405 and the vertical magnet M4|4.

When ground potential is applied to the control conductor C364 of thetrunk 360 an obvious circuit is completed for energizing the upperwinding of the transfer relay R485, thereby to cause the latter relay tooperate. Upon operating, the transfer relay R435 prepares, at thecontacts 403, a further point in the previously mentioned circuit forenergizing in multiple the lower winding of the transfer relay R485 andthe vertical magnet M4|4 and completes, at Athe contacts 486, an obviouspath for applying ground potential to the control conductor C363 of thetrunk 350. This application of ground potential to the control conductorC363 of the trunk 360 prepares a circuit traced hereinafter forenergizing the winding of the stop relay R350 in the nder switch 300 andcompletes a circuit for energizing the winding of the rotary magnet M393of the sequence switch 380. The circuit for energizing the rotary magnetM393 of the sequence switch 380 extends from the grounded controlconductor C353 of the trunk 360 by way of the contacts 35| and 319, theconductor C321 in the cable 320, the contacts 394 and the rotary magnetM393 to battery. When thus energized the rotary magnet M393 operates tocondition the wipers noted of the sequence switch 380 to be driven onestep in the clockwise direction and to interrupt, at the contacts 394,the previously traced circuit for energizing the rotary magnet M393;whereupon the rotary magnet M393 restores to drive the wipers noted ofthe sequence switch 300 one step in the clockwise direction and torecomplete, at the contacts 394, the previously traced circuit forenergizing the rotary magnet M393. Accordingly, the rotary magnet M393operates intermittently, thereby to drive the wipers noted of thesequence switch 380 step by step in the clockwise direction until thestop relay R350 is operated in a manner more fully described hereinafterto interrupt, at the contacts 35|, the previously traced circuit forenergizing the rotary magnet M393.

At this point it is noted that, immediately the link distributor 30|assigns the link illustrated to the use of the calling subscribersubstation T|, operations of the iinder switch 300 and the selectorswitch 400, previously described, are initiated, and that the operationof the selector switch 400 initiates operation of the sequence switch380 individually associated with the link illustrated. Accordingly,operation of the sequence switch 300 to find an assigned one of the Aoperator positions or to find a storage position in the call storageunit 600 is initiated prior to the seizure of the telephone line 205extending to the calling subscriber substation Tl by the finder switch309.

Prior to continuing with the operation of the sequence switch 380, it isnoted that the A operator position distributor in use, the main Aoperator position distributor 630 in the present example, is operativeto preselect an idle one of the A operator positions to be seized by thesequence switch 330. Assuming that the iirst A operator position590 hasbeen preselected by the main A operator position distributor 630 to beseized by the sequence switch 380 at this time, a holding circuit iscompleted for energizing in series the winding of the hold relay R610and `the `right-hand winding of the Aposition relay R630, -the positionrelay R630 corresponding to the rst A operator "position 500. Thisholding circuit extends from ground by Way ofthe contacts 55|, C50|, thecontacts 534 of the Azoperator position distributor key K530, C653, thewinding of R610, the contacts 646 and 634 and the right-hand winding ofR630 to battery. The operated position -relay R530iretains interrupted,at the contacts 635 a `holding circuit traced hereinafter for energizingthe winding of the hold lrelay R610 in series with the right-handwinding and the contacts 559 to the control conductor C525 of the trunk520 extending to the iirst A operator position 5150 and completes, atthe contacts 53|, a path for applying ground potential to the controlconductor C630, for a purpose more fully described hereinafter. The pathfor applying ground potential to the control conductor C680 extends fromground by way of the contacts 545, C656, the contacts 63|, C635 and thecontacts 592 of the A operator position distributor key K530 to thecontrol conductor C500. Further it is noted that no potential Whateverappears upon the marking conductor C530 to C535, inclusive; whilebattery potentialappears upon the marking conductor C535. The path forapplying battery potential to the marking conductor C536 extends frombattery by way of the winding of the, rst marking relay` IM and thecontacts 62| to the marking conductor C535.

Continuing .now with the operation of the sequence sWl/Qh 350, therotary magnet M393A continues to operate intermittently in order todrive the wipers noted of the sequence switch 350 step by step in theclockwise direction until the wiper 30| engages the seventh contact inthe associated contact bank 352 terminatingv the marking conductor C536;whereupona circuit is, completed forenergizllg, inr series the windingof the stop relay R350 and the winding of the marking relay IM. Thiscircuit extendsfrom the grounded control` conductor C363 of the trunk360 by way of the windingof R350, the contacts 311, the controlconductor C325 in the cable 32,0,.the wiper 39| and engaged seventhcontacty in the associated contact bank 332 of the sequence switch 380,the marking conductor C536, the contacts 62|` and the winding off IM torbattery. When the winding of the stop relay R3501is thus energized, thisrelay operatesto interrupt, at the contacts 35|, the previously tracedcircuit for energizing the rotary magnet M393, thereby positively toarrest further operation of the sequence switch 385;

When thewinding ofthe marking relay |M` is thus energizedthis relayoperates shortly thereafter, this Vrelay being ofthe slow-to-operatetype,

' to complete, at the contacts |M2, a circuitfor energizing the windingofV theY release relay R625,V

`Also the release relay'R62`0 completes, at the contacts 623, an obviouscircuit for energizing the winding of the control relay REID, therebyYto cause the latter relay to operat'eshortly thereafter, the `latterrelay being of the slow-to-operate type. Further the release relay R`620inte`r rupts, at the contacts 62|, the previously ytraced circuit forenergizing in series the winding of the stop relay R355 and the windingof the niarking :relay IM. Upon operating, the control'relay R5|0completes, at the contacts 6| I, an obvious path for applying batterypotential by way of the Winding of the marking relay IM to the markingconductor C536. Y

Accordingly, the marking -relay IM and the stop relay R355 restore whenthe previously traced circuit for energizing iin series the windingsthereof is interrupted incident to the operation of the release relayR520. Upon restoring, the stop relay R550 completes, at the contacts35|, the previously traced circuit for energizing the rotary magnet M593of the sequence switch 350, thereby to cause the rotary magnet M353again to operate intermittently. In the present instance, the rotarymagnet M353 operates and restores only once; whereupon the wiper 33|thereof engages the eighth Contact in the associated contact bank 332 ofthe sequence switch 380 terminating the control conductor C525 of thetrunk 525, thereby to complete a series circuit for energizing thewinding of the answer relay R555 and the winding of the stop relay R353;This circuit extends from the grounded control conductor C353 of thetrunk 355 by way of the winding of R355, the contacts 311, the controlconductor C325 in the cable 325, the wiper 375| and engaged eighthcontact in the associated contact bank 392 of the sequence switch 380,the control conductor C525 of the trunk 520, the contacts 555, thewinding of R555, C532, the contacts 532 and the resistor 5|2 to battery.When this series circuit is completed the windingsof the stop relay R353and the answer relay R555 are energized, thereby to cause these relaysto operate. Upon operating, the stop relay R355 again interrupts, at thecontacts 35|, the previously traced circuit for energizing the rotarymagnet M355 of the' sequence switch: 355, thereby again to arrestoperation of the sequence switch :5 335. Upon operating, the answerrelay R545 interrupts, at the contacts 556, the previously tracedholding circuit for energizing the winding of the release relay R523,thereby to cause the latter relay to restore and interrupt, at thecontacts 523, the previously mentioned circuit for energizing thewinding of the control relay RSIEI, thereby to cause the latter relay torestore. Also the answer relay R555'completes, at the contacts 551, anobvious circuit for energizing the winding of the disconnect relay R555,thereby to cause the latter relay to operate.

Upon operating, the disconnect relay R555 completes, at the contacts552', a holding circuit for energizing the winding thereof, this circuitextending from ground by way of the contacts 55'i of the trunkdisconnect key K550, the contacts 552 and the winding of R553 tobattery. Also, the Adisconnect relay R555 interrupts, at the contacts555, the previously traced circuit for energizing in series the windingof the stop relay R555and the winding of the answer relay R555 andcompletes, at the contacts 557, a circuit for energizing the winding ofthe cut-in relay R310, this circuit extending fromground by way of thecontacts 551, the control-conductor C525 of the trunk 520, the wiper 38|and engaged contact in the associated contact bank 382 of the sequenceswitch 380, the control conductor C326 in the cable 320 and the windingof R310 to battery. When thus energized the cut-in relay R310 operatesto interrupt, at the contacts 311, a further point in the previouslytraced series circuit for en ergizing the winding of the stop relay R350and the winding of the answer relay R545, to prepare, at the contacts318, a circuit traced hereinafter for energizing the winding of theidentity relay R360 and to interrupt, at the contacts 313, a furtherpoint in the previously traced circuit for energizing the rotary magnetM303 of the sequence switch 380. The stop relay R350 and the answerrelay R545 then restore. Accordingly, at this time, the wipers noted ofthe sequence switch 380 engage the contacts in the associated contactbanks thereof terminating the conductors of the trunk 520 extending tothe rst A operator position 500.

Further, the disconnect relay R550 interrupts, at the contacts 553, anobvious connection between the line conductors C521 and C523 of thetrunk 520, interrupts, at the contacts 555, an obvious connectionbetween the line conductors C522 and C524 of the trunk 520, completes,at the contacts 55| and 552, a connection between the conductors C521and C523 of the trunk 520 and the retarder coil 530 and the telephoneapparatus 511 at the first A operator position 500, and completes, atthe contacts 554 and 555, a connection between the line conductors C522and C524 of the trunk 520 and the retarder coil 530 and the telephoneapparatus 511 at the rst A operator position 500. Accordingly, at thistime, one terminal of the retarder coil 530 is connected by way of thecontacts 531 and 551 and by way of the contacts 542, 531 and 554 to theline conductors C521 and C522, respectively, of the trunk 520; and theother terminal of the retarder coil 530 is connected by way of thecontacts 533 and 552 and by way of the contacts 544, 538 and 555 to theline conductors C523 and C524, respectively, of the trunk 520. Also thetelephone apparatus 511 at the rst A operator position 500 is connectedby way of the contacts 511 and 513 across the terminals of the retardercoil 530.

Upon operating, the cut-in relay R310 completes, at the contacts 312 and315, an alternative loop circuit extending between the retarder coil 530at the rst A operator position 500 and the line relay R450 in theselector switch 400, this circuit extending from ground by way of thelower winding of R450, the contacts 466, 433 and 428, C362, the contacts315, the line conductor C324 in the cable 320 and the wiper 335 andengaged contact in the associated contact bank 386 of the sequenceswitch 380 to the line conductor C524 of the trunk 520, and from batteryby way of the upper winding of R450, the contacts 463, 431 and 426,C361, the contacts 312, the line conductor C332 in the cable 320 and thewiper 380 and engaged contact in the associated contact bank 330 of thesequence switch 300 to the line conductor C522 of the trunk 520, theline conductors C522 and C524 of the trunk 525 being connected togetherby way of the previously traced path including the retarder coil 530.Also the cut-in relay R510 completes, at the conta/cts 31| and 314, aconnection between the subscriber substation T1 and the line conductorsC521 and C523 of the trunk 520. More particularly, the line conductorC206 of the telephone line 205 is connected by way of the wiper 314, thecontacts 331 and 311, the line conductor C321 in the cable 320, and thewiper 331 and engaged contact in the associated contact bank 383 of thesequence switch 330 to the line conductor C521 of the trunk 520; whilethe line conductor C201 of the telephone line 205 is connected by way ofthe wiper 315, the contacts 332 and 314, the line conductor C323 in thecable 320 and the wiper 383 and engaged contact in the associatedcontact bank 334 of the sequence switch 360 to the line conductor C523of the trunk 520. Finally, it is noted that a bridge at the subscribersubstation T1 is connected across the line conductors C206 and C201 ofthe telephone line 205; while the line conductors C521 and C523 of thetrunk 520 are connected to the retarder coil 530. Accordingly, at thistime, a direct loop circuit is completed between the retarder coil 530at the rst A operator position 500 and the line relay R450 in theselector switch 400; while an alternative loop circuit is completedbetween the subscriber substation TI and the line relay R450 in theselector switch 400 which includes the trunk circuit at the rst Aoperator position 500. Also when the telephone apparatus 511 at thefirst A operator position 500 is bridged across the retarder coil 530 aconnection is completed between the calling subscriber substation T1 andthe telephone apparatus 511.

Further the cut-in relay R310 interrupts, at the contacts 313 and 316,the previously traced direct loop circuit between the subscribersubstation T1 and the line relay R450 in the selector switch 400,interrupts, at the contacts 3'10, a point in a holding circuit tracedhereinafter for energizing the winding of the call back relay R440 inthe selector switch 430, and interrupts, at the contacts 311', a pointin a circuit traced hereinafter for energizing the winding of the coinand register relay R430 in the selector switch 400. Finally the cut-inrelay R310 completes, at the contacts 312', an obvious alternativeholding circuit for energizing in series the lower winding of theswitching relay R330 and the rotary magnet M301, and interrupts, at thecontacts 313', the previously traced original holding circuit forenergizing in series the lower winding of the switching relay R330 andthe rotary magnet M351. Accordingly, the operated cut-in relay R310retains the switching relay R330 in its operated position independent ofthe selector switch 400, thereby to retain the finder switch 300 in itsoperated position independent of the selector switch 400.

Also, upon operating, the disconnect relay R550 completes, at thecontacts 551', a circuit for energizing the winding of the tone relayR510, this circuit extending from ground by way of the contacts 551 and528 and the winding of R510 to battery. When the winding of the tonerelay R510 is thus energized this relay operates shortly thereafter,this relay being of the slow-to-operate type, to complete, at thecontacts 515, an obvious circuit for energizing the winding of the tonerelay R520. When thus energized the tone relay R520 operates shortlythereafter, this relay being of the slow-to-operate type, to complete,at the contacts 523, an obvious circuit for energizing the winding ofthe tone relay R525. When thus energized the tone relay R525 operatesshortly thereafter, this relay being of the slow-to-operate type, tocomplete, at the contacts 521, an obvious holding circuit for energizingthe winding thereof and to interrupt, at the contacts 523, thepreviously traced circuit for energizing the winding of the tone relayR|0 The One relarlillihen restores t0 interrupt,

circuit for f energizing the `Winding of Y the ,tone

relay R520, therebyto restore. K -f g ,1

. 4Upon operating, the tone relay R5l0 interrupts, at the contacts, 5I Iand 5l3, thepreviously traced connection between, the telephoneapparatus 5|1 andthe retarder coil 530 and cornpletes, at thecontacts512 and 5I4,.,a -circuit for conducting tone,I current ,over` theAtelephone apparatus 5|1i 'Ihe last-.mentioned circuit extends `from the,ungroundedgterminal of a grounded sourceof tone` current, not shown,.byWay` of the causeA `the latter, relay to tone conductor C581, thevcontacts 522 and 5I2,

the telephone apparatus 5|1, the contacts 514 and the condenseny 516 toground. vUpon. operating, the Atone relay R520` interrupts, at thecontacts 522,` the previously `traced :circuit for conducting tonecurrent 'over the telephone aptive circuit for conducting tone currentover the telephoneapparatus 5|1, this alternativecircuit extending fromtoneA potential-appearing upon the tone conductor C581 by way of thecontacts 526, 52|` and 5|2, `the telephone apparatus 5H,

the contacts 5i 4 and the condenser 5 l 6 to ground. Upon restoring, thetonerelay R5i0 interrupts, at the contacts 512 and 5|4, the previouslytraced alternative. circuit for conducting tone current over thetelephone apparatus 5I1 and recompletes, at the contacts 5H and 5i3, thepreviously traced connectionbetvveen the telephone apparatus 5H andtheretarder coil 53,0. Finally, upon restoring, the tone-'relayR520interrupts, at the contacts 521, a furtherpoint in the Apre- Viouslytracedalternativeprcuit for conducting tonev current over thetelephoneapparatus 5I1 and prepares, at- Ithe contacts 522, thepreviously `*traced original circuit for conducting tonecurrentovertheutelephone apparatus 531. The o'per-'ation-ofY the tonerelays R5l0, R520 and R525 andthe Vsubsequent restoration of thetonerelays R5I0 and R520 is eiective to cause the receiver of thetelephoneinstrument,included in the telephone apparatus 511 to beoperated alternately,` Whereupona distinct zip-zip tone is producedthereby. lThe production of the zip-ziptone by the receiver of thetelephone instruinentl included in themtelephone apparatus iilfi'A atthe first A operator position k550,indicates to the operator thereatthat an incoming call has been extended to herpovsition by one of thesequence switches. j

Further, upon operating, the disconnect relay R550 prepares, `attire,contacts 555?, a` point in chain circuit.tracedhereinafter forenergizing the Winding of 'thebusy relayv R550,V which chain circuit is.completed-in the event all of the A" to battery;vl When thus`energized;` the. position lil A operator position 500 tothe Vcontrolconductorrelay R640 operates to complete, at the contacts 64.4, aholdingcircuit for.4 energizing in, series the windingotfthehold relay R610 andthe righthandi.,winding of thefposition relay R640,this `circuitiextending vfrom ground by Way of the contacts. 56I,C50I, the contacts5940i the A .operator position distributorkey K500, C683, the Winding ofR610,\thecontacts 656' and 644 and the right-hand Winding of R640 4tobattery. Alsothe position relayiR640 interrupts, at the ,contacts 646,the previously. traced holding circuit for energizing in series thelwinding of the hold relay. R610 and the-right-hand Winding ofthepositiony relayfR630, thereloyv to cause f-the latter relay to.restore. Further the position relay R640 prepares, at the contacts 643,anobvious .circuit forenergizing `the left-hand Windingof thepositionrelay R650 corresponding to the last A operator position,lcompletes, at the contacts 642,Y an obvious path for applying batterypotential to the control conductor C61| extending to the second Aoperator position and corresponding to the control conductor C682extending to the rst` A operator position 500 and completes, at thecontacts 64|, an obvious* path forrapplying ground-potential at thesecond A"A operator position to the'control conductor C680, in `a'mannersimilar to lthatfpreviousl-y explained. Accordingly,rthe operation ofthe position relay R540--inthe fmain ',Aoperator-'positiondistributor'si is effective toprepare the secondiA operatorpositionitoreceive the next incoming call vin` theevent the second -Aoperator position is idle atA this time. On the other hand, in theev'ent theseoond A operator position is busy at this ttime,theprev-iouslymentioned circuit for energizing the left-hand Winding ofthe position relay R650 is completed at the contacts 653 incident totheoperation ofthe position relay R540, the disconnect relay at: the secondA operator position being operated at this time. Further it isfnotedthat, upon restoring, the position relay :R630 interruptaat the contacts634, a further pointin thev previously traced holding circuit forenergizing in series rthe Winding-of the hold relay R5`1ElandV the`right-hand winding of the -positionirelay R530.V Also the positionrelay R530 interrupts, at the contacts 633, the previouslytraced circuitfor energizing the lefthand Winding of theposition relay R50,"int`erirupts, at the contacts 532,1a further point inr the previously tracedcircuit'for energizing the Winding offthe answer relay R545-andinterruptsg'at the contacts G3i; thepreviusly traced original circuitfor applying groundpotential at the first v "At this point it is notedthat the main A operatori position l distributor 630- is` operated,thereby to causetone of the position relays to operate and condition acorresponding oneof` the A operator positionszto receive the nextincoming call, such, forexample, asthe second Aoperator position, onlyyinl-the event oney of` the A operator positions is idle atthis time; 1More particularly, Vin

t the event all of the-A operator positions are busy When thedisco'nnectrelay'R550 is operated, Athe previously mentioned-chain circuit forenergizing the Winding-fof the busy: relay R560l is completed atthecontactsv 553 incident to the operation ofthe'disconnect-=relay1R550. This circuit'extendsfrom ground 'by way ofthe chain conductor C519,-the contacts ofA the disconnect relaysYatcth'e other A operator positions, the

contacts 553 ofthe disconnectfrelay R550 at the rst A operator position500 and the winding of R560 to battery. When thus energized the busyrelay R560 operates to interrupt, at the contacts 56|, the previouslytraced holding circuit for energizing the winding of the hold relay R610in series with the right-hand winding of one of the position relaysR630, R640, R650, etc., thereby to cause the hold relay R610 to restoreand all of the position relays R630, R540, R650, etc., to remain intheir restored positions. Also, upon operating, the busy relay R560interrupts, at the contacts 552, a point in an alternative circuit forenergizing the left-hand winding of the position relay R630. Uponrestoring, the hold relay R010 prepares, at the contacts 61|, a point inthe previously mentioned alternative circuit for energizing theleft-hand winding of the position relay R635. Accordingly, the operationof the busy relay R560 is effective to prevent further operation of themain A operator position distributor 630 until one of the A operatorpositions becomes idle.

When one of the A operator positions becomes idle the disconnect relaythereat is restored, thereby to interrupt the previously traced circuitfor energizing the winding of the busy relay R500, whereupon the latterrelay restores. Upon restoring, the busy relay R560 prepares, at thecontacts 55|, the previously traced holding circuit for energizing thewinding of the hold relay R610 in series with one of the position relaysR630, R640, R650, etc., and completes, at the contacts 652, thepreviously mentioned alternative circuit for energizing the lefthandwinding of the position relay R630, this circuit extending from groundby way of the contacts 502, C502, the contacts 595 of the A operatorposition distributor key E590, C684, the contacts 61| and the left-handwinding of R630 to battery. When this circuit is'completed the positionrelay R630 operates, thereby to initiate further operation of the main Aoperator position distributor 630; whereupon the main A operatorposition distributor 630 operates in order to cause the particular oneof the position relays R630, R540, R650, etc., to remain operated, whichcorresponds to the idle A operator position, thereby to condition theidle A operator position to receive the next incoming call.

Further it is noted that the operation of the auxiliary A operatorposition distributor 605 is the same as the main A operator positiondistributor 630, previously explained. In the event the main A operatorposition distributor 630 becomes defective, the operator at the first Aoperator position 500 may substitute the auxiliary A operator positiondistributor 695 for the main A operator position distributor 630 byoperating the A operator position distributor key K590. When the Aoperator position distributor key K590 is thus operated the previouslytraced connections between the control conductors C684, C603 and C655extending to the main A operator position distributor 650 and the commoncontrol conductors C502, C50| and C680 are respectively interrupted atthe contacts 595, 594 and 592 of the A operator position distributor keyK595i); and obvious alternative connections are completed, at thecontacts 596, 503 and 59| of the A operator position distributor keyK590, between the common control conductors C502, C50| and C680 and thecontrol conductors C693, C692 and C09I, respectively, extending to theauxiliary A operator position distributor 695.

Accordingly, at this time, after the sequence switch 389 seizes thetrunk 520 extending to the rst A operator position 500 and both theapparatus at the iirst A operator position 500 and the main A operatorposition distributor 630 operate in the manner previously explained, aconnection is established between the calling subscriber substation TIand the telephone apparatus 5|? at the first A operator position 500 andthe second A operator position is conditioned to receive the nextincoming call. More particularly, both the receiver and the transmitterat the telephone instrument included in the telephone apparatus 5|1 areoperatively connected to the subscriber substation Ti. Accordingly, theoperator at the rst A operator position 500 may converse with thesubscriber at the calling subscriber substation T| and ascertain thedestination of the call. After learning the destination of the call, theoperator at the rst A operator position 500 initiates the extension ofthe call by operating the key sender K520 in order appropriately tocontrol the selector switch 400 in a manner more fully describedhereinafter.

Paystatz'on call A call from a paystation, such, for example, as thepaystation T2, is initiated by removing the receiver of the telephoneinstrument thereat from its associated switchhook and depositing a coinin the coin slot of the coin collect and refund mechanism thereat. Whenthe receiver of the telephone instrument at the paystation T2 is removedfrom its switchhook and the coin is deposited in the coin slot of thecoin collect and refund mechanism thereat, a bridge path is completedbetween the line conductors C246 and C241 of the telephone line 245extending to the paystation T2, thereby to complete a circuit forenergizing in series the upper and lower windings of the line relayR250. This circuit extends from ground by way of the contacts 281, C294,the lower winding of R250, the contacts 262, C241, the bridge pathbetween the line conv ductors C241 and C246 of the telephone line 245253, a path for applying ground potential to the control conductor C249of the telephone line 245, thereby to mark the telephone line 245 asbusy to the rst B operator position 494 and the other B operatorpositions in the local exchange 20. I'he last-mentioned path extendsfrom ground by way of the contacts 281, C294 and the contacts 253 and214 to the control conductor C249 of the telephone line 245. Also theline relay R250 completes, at the contacts 252, an obvious multiple pathfor applying battery potential by way of the winding of the cutoff relayR260 and the resistor 261 to the control conductor C248 of the telephoneline 245, thereby to mark the telephone line 245 as a calling line.Further the line relay R250 completes, at the contacts 25|, an obviouspath for applying direct ground potential to the marking conductor C284terminated by the i'ifth contacts in the vertical control Contact banksof the finder switches, thereby to mark the telephone line 245 asterminating in the fifth level of the main contact banks of the finderswitches. Finally, the line relay R250 cornpletes, the contacts 25|, apath for applying resistance ground potential to the start conductorC308 extending to the link distributor 30|, this path extending fromground by way of theentacts" and 2f|l,`C234, the resister andthe`-contacts288 to the start conductor C308, Theapplication of groundpotential-to the start conductor C308 initiates operation of the linkdistributor in the manner previously explained.- A

`The-link distributor 33| then operates `to cause the previouslyselected link to be assigned to thei'iise of the calling paystation T2in the pre- Viouslydescribed manner. Assuming that the linkdistributor30| operates to assign the link illustrated to the use of the callingpaystation T2, the finder switch 303 operates in the manner previouslyexplained toseize the" telephone liner 245 extending to the callingpaystationT2, Also the 'selector switch' 490 and the sequence switeh 380operate in the manners-previously described.`

Assuming that the main A operator position dis-` tributor" G30 haspreviously selected the LfirstAf operator position 500 at this time,the'sequence switch`380 operates to seize the trunk 5205 extending tothe iirst A operator position 538m themanner previously explained. l'

When the first `A operator position 500 seizedvb'y the sequence switch380 the cut-in re-l lay R328 operates in order tocompletefat thecontacts 372 and 325, the previously traced`loop circuit between theline relay R450 inn the selector switch 400 and the retarder coil 530 atthe first A operator position 508, and to completeat` the contacts 3l|and 314, a loop circuit between the calling paystation T2l and theretarder coil 533 at the rst A operator position 530.

way of the wiper 3|4, the contacts 33| rand 31|, the line conductor C32|in the cable 328, the

wiper 331 and engaged contact in the associated contact bank 338 of thesequence switch 380,

the line conductor (252| of the trunk 520, the

contacts and 53|; the retarder coil 530, the contacts 533 and 552, thelin'conductor`C523 of the trunk 520, the wiper 383 and engaged contactinthel associated contact bank 384 of the sequence switch 338, the lineconductor C323 in the cable 320, the contacts `3"|4 and 332 'and theWiper 3|5 to the line conductor C2llll'cf`tl'1ey telephone line 245, theline conductors C245 and C24? ofthe telephone line 245 being connectedtogether by Way of the bridgepath at the calling paystation T2.

Also; when the finder switch 300 seizes the telephone line 245,directground potential is applied by way'of the wiper'3l6 tothe controlconductor C248 of the telephone line 245, there# by Vto complete acircuit for energizing the Winding "ofl the cutoff relay R250,`thiscircuit extending from the grounded control conductor 0248er the?telephone line 245 `by Way `of the contacts 252`and 26 and the Windingof R260 to battery. When thus energized the cutoff relay R260 opcratesto complete, at the contacts 204, an obvious The last-'f mentioned loopcircuit extends from the line conductor C240 of the telephone line 245by` circuit v,for energizing inV series ,th'ejupper and lcnyerl,windings of` the line` relay, R258, thereby ,to caus'ethe' latterlrelayito restore, andjfree the telephoneline 245 of impedanceelements.` ,Upon rest ng, theliner relay R250 interrupts; at thecontacts25h'the previouslyA mentioned path for applying" directgroundpotential to the `markmg conductor o 'zaa and the previouslyltracedf path" 'applying resistance lground potential to eifstartconductor C308; in order tov remove the ",n'iarking from the telephoneline 245V and to stmfnrther operation ofA the" link distributor elvUnpon operating,` the lockout relay R210 s, at the contacts 212, apoint in aholding circuit traced hereinafter forenergizing the windingthereof and co,npletes,`V at thecontacts a 223, an obvious 'alternatiVeUpath for, ,applying ground potential to the control'onductor C249 oftlietelephone `line 245, 'therebyto mark the `telephone'line 245 as busytothe `Boperator positionsA in the local nexchange V20 having accessthereto. Finally, ,thelockout relay` R2l0pre- Iparesatithe contacts 215,a further point in the previously mentioned circuit for illuminating thesignal lamp L258. l I

The'operator at thev first A operator position 4"ll0` tl'ien answers theeall'andis advised con- "cernirig' the extension of 'the call by thesubing ground potential tothe, control` Conductor holding circuit forenergizing the winding thereof by way of the :control conductor C248 ofthe telephoneline 245, to interrupt, at the contacts 265, the previouslytraced path for applying bat-Y tery potential by Way of the resistor 201tothe control conductor C248 of the telephone line`4245,

and to interrupt, at the contacts 266, a pointin a circuit tracedhereinafter for illuminating the Also the cutoff relay R260 signal lampL2$8. l K completes, at the contacts 283, an obviousV circuitfor'energizing the winding of the lockout `relay Ril, thereby to Vcausethe latter relay to operate. Finally the cutoi relay R260 interrupts, at

scriberat the calling paystation T2. After learning,*thedestination.ofAthe call the operator` atV thefirrstuA operatorposition 530 initiates'the extensionof the call by operating the keysender IIZ52f0in orderappropriately to control thesein a manner more fully denetwork'ZBQ,whereupon the latter relay restores; Upon restoring, theabusy` relayR285 interrupts,

atvthefcontacts 231,l an obviousp'ath for` apply C2544 andan olfmjeus--patnfcr ,short-`ciicuitingA the secondary winding 292er thetone trans-`former 4290, the primaryuwindinglj of thetone trans'rfomer 200 beingeonnectedjtova suitable` ,tonejfcurrent not shown.' f Hence, wat, this`time,

the, (intacts A25| 2,32, thew'previously,tracedground` 'potential isAremoved :from ,thefcontrol` conductorl C2 9 4 andtonefpotentilal appearsthere'- on. \Alsoupon restoring, the busy. relay` R205 intrruptscat thecomme 235,1. a'jnoint `in the prevliously4 'traced Vpathv `forapplyin'g'resistance ground potential to'the start, conductorv'Ca y extending to'tne link 'distributor t35a] 5 e ln the"e`vet a callw is initiatedatfone of the "siibscrilierv substatiisfqr paystauons at this tirri'e a'circuit is` completed'fer pr(')jecting busy tone rentto the subsrbefSubst'atien or paystatiqgilver -theassqeiated telephone une, For

subsane subsanar a therme@ .circuit is completed for projecting busytone current over the telephone line 205 to the subscriber substa-

